Interstate 270 — 5.5 miles long; spur from I-70 east of downtown Denver, CO, to I-76 north of downtown; shortcut from the east side of Denver to the Denver-Boulder Turnpike (U.S. Route 36); numbered in reverse (zero point at I-76, highest numbering at I-70); I-70 Exit 279 (from westbound I-70 only)

Interstate 470 — 14 miles long; 180° loop, south of I-70, bypassing downtown Topeka, KS; easternmost 7 miles part of the tolled Kansas Turnpike; termini at I-70 Exit 355 and I-70 MP 367 (no exit number at east end)

Interstate 670 — 3.5 miles long; functionally a 180° loop south of I-70, but more accurately serves as a straighter through route than I-70, which has one notoriously tight curve on the Kansas side; covers the south side of downtown Kansas City’s “Alphabet Loop” of freeways; termini at I-70 KS Exit 421B and MO Exit 2L

Interstate 270 — 50 miles long; covers southwestern, western, and northern 5/8ths of the outer loop around St. Louis, MO; specifically, northern segment is the I-70 bypass avoiding downtown; uses the Chain of Rocks Bridge to cross the Mississippi River; exit and mile numbering reset to zero upon entering Illinois (34 miles in MO, 16 miles in IL); begins at I-55 in Mehlville, MO, south of St. Louis; crosses I-70 Exit 232 in Bridgeton, MO, at I-270 Exit 20; then eastern terminus at I-55/70 Exit 20 in Troy, IL

Interstate 670 — 11 miles long; spur from I-70 on the west side of Columbus, OH, to I-270 near Port Columbus International Airport east of the city; serves as the northern part of Columbus’ freeway “innerbelt”; I-70 Exit 96

Interstate 470 — 11 miles long; 180° loop, south of I-70, bypassing downtown Wheeling, WV; also bypasses the Wheeling Tunnel, which has only one I-70 through lane in each direction and prohibits trucks hauling hazardous materials; numbering resets upon entering West Virginia (6 miles in OH, 5 miles in WV); termini at I-70 OH Exit 219 and WV Exit 5

Interstate 270 — 32 miles long; spur from I-70 at Frederick, MD, to I-495/Capital Beltway in Bethesda, MD; also has its own 1½-mile spur (I-270 SPUR) to serve traffic utilizing I-495 to or from the west, as mainline I-270 only connects with I-495 to and from the east; numbered in reverse (zero point at I-495, highest numbering at I-70); I-70 Exit 53

Interstate 370 — 3.4 miles long; spur that “spears” I-270 (exists on both sides of I-270); largely exists to connect I-270 with a park and ride lot at I-370’s east end; crosses I-270 Exit 9 at I-370 Exit 2 (does not connect to I-70)

NOTE: Independent cities are in ALL CAPS and are noted with “CITY OF ____.”

A quick hypertext drive: Fifth-longest among America’s Interstate highways, Interstate 70 is a true study in contrasts. It spans both the low, flat cornfields of the Midwest and the Rocky Mountains of Colorado; it reaches not only the peak elevation of the whole system, but also the depths of ignominy when over 2,000 miles of highway come to an end in a park and ride lot.

Interstate 70 begins in the middle of nowhere at I-15 in Cove Fort, UT, literally 30 miles from any signs of civilization in any direction. Almost immediately, I-70 begins to climb through the Wasatch Range, which runs parallel to and just east of I-15 through much of Utah. After reaching Salina Summit at 7,923 ft. (2,415 m), I-70 starts to descend into a lower, flat area with a few towns, most notably Richfield and Salina. These two towns are good places to stop, because after Salina, it’s 106 miles (171 km) to the next gas station, restaurant, motel, or any other service in Green River — this is the longest such no-services stretch of Interstate anywhere in America.

That said, this long no-services stretch is still an amazingly beautiful drive with some of the best scenery anywhere in the West. Just to the east of Salina, I-70 runs through a canyon and curves around a lot; this stretch is especially beautiful in winter, with snow on the hillsides. Further east, the highway runs through a straighter but more mountainous stretch for a while, with the reddish rock that covers much of the Southwest on display for travelers. An especially striking segment of the road runs through Rattlesnake Canyon (also called Spotted Wolf Canyon), between mileposts 138 and 145 — about 15 miles (25 km) west of Green River. There is a fairly long and steep grade — descending eastbound, climbing westbound — here.

After coming out of Rattlesnake Canyon, I-70 becomes fairly flat and (by comparison, at least) boring for most of the rest of Utah. There aren’t even that many numbered highways that cross I-70 here; many of the exits are otherwise unnamed “ranch exits” for unpaved roads that connect to the huge ranches in the area. The flat part of I-70 continues into western Colorado, although there are mesas and mountain peaks visible on both sides of the highway.

The next major feature of I-70 is De Beque (pronounced duh-BECK) Canyon, located east of Grand Junction between mileposts 46 and 58; the highway runs with the upper Colorado River through the canyon, crossing the river several times and passing through some short tunnels blasted through the canyon walls. After leaving De Beque Canyon, I-70 returns to flatter surroundings similar to those in eastern Utah; it does continue to more or less parallel the Colorado past several small towns.

At milepost 119, a few miles east of the town of Glenwood Springs, I-70 enters into Glenwood Canyon. This 14-mile (22 km) stretch of the highway cost well over $1 billion to build and was not completed until 1992, some 10-15 years after most of the rest of the Interstate system, but it is perhaps the greatest engineering marvel of the entire system. The highway is essentially cantilevered into the canyon wall on the north bank of the Colorado River; in many places, the westbound lanes run almost directly above the eastbound lanes for lack of space between the canyon wall and the river. Retaining walls are used extensively to prevent the westbound roadway from sliding down the mountainside; still, falling boulders can be an occasional hazard, such as the one that closed I-70 here in spring 2005. There is a 50 mph (80 km/h) speed limit here for passenger cars, and 40 mph (64 km/h) for heavy trucks, due to the almost constant back-to-back extremely tight curves.

Near the old railroad siding of Dotsero, at milepost 133, I-70 exits Glenwood Canyon and becomes fairly straight and flat again. Leaving the Colorado River, it begins paralleling the Eagle River past the towns of Gypsum and Eagle, gradually increasing in elevation as it goes east. The highway passes literally right through the center of the world-famous ski resort of Vail, which more or less owes its entire existence to I-70 and the two-hour trip from Denver that I-70 facilitates. After passing through Vail, I-70 starts climbing into the heart of the Rockies, eventually reaching the 10,666-ft. (3,251 m) summit of Vail Pass near milepost 191. For some reason, I-70 dips well to the south between Vail and Silverthorne instead of following a direct path; I surmise that a direct route would have been even more difficult to construct than what was eventually built.

Staying near the 9,000-ft. (2,743 m) level, I-70 passes through Frisco, Dillon, and Silverthorne, a few more ski towns, before beginning a long, very steep, and treacherous climb toward the Continental Divide. (The westbound descent here gets as steep as 8%, and trucks are limited to 30 mph (48 km/h) headed down the hill.) The Eisenhower-Johnson Memorial Tunnel, named for both the figurative father of the Interstate system and a Colorado governor who was instrumental in getting I-70 extended west of Denver, carries I-70 underneath the Divide at milepost 214; its western portal, at 11,192 ft. (3,411 m), is the highest point on the entire Interstate system. At this elevation, it takes bulldozers instead of plow trucks to keep I-70 clear of snow in the winter; roadside snow piles are often 25 feet (8 m) or more high.

(Because the Eisenhower-Johnson Tunnel was built in the 1970s, it lacks fire-suppression equipment and therefore prohibits trucks hauling hazardous materials. In most circumstances, these vehicles must exit in Silverthorne and use the switchback-laden U.S. Route 6 over the even higher Loveland Pass (11,990 ft./3,655 m), and rejoin I-70 a few miles east of the tunnel. If Loveland Pass is closed by snow, haz-mat trucks must stop before entering the tunnel, and every hour or so, the Colorado State Patrol closes the tunnel and escorts these vehicles through at a very low speed.)

The descent on the east side of the Divide is a bit less steep, although I-70 still descends at an average rate of about 2% into Georgetown. The highway runs through the Clear Creek Canyon from there to about Idaho Springs, after which it goes through some tight 45-mph (72 km/h) curves and begins to climb Floyd Hill. For about seven miles (11 km) from Floyd Hill, there are a number of short climbs and descents; near milepost 255, though, I-70 begins a dramatic steep, winding descent that brings it directly into the Denver metropolitan area. The contrast is absolutely amazing — in five miles, you go from mountain wilderness into suburbia. There is a 55-mph (88 km/h) speed limit for passenger cars and a 35-mph (56 km/h) limit for large trucks descending this grade, although many car drivers ignore 55 and scream down the hill, making things dangerous for everybody else. That said, I don’t think a text description of the Vail-to-Denver segment of I-70 can truly do it justice — its stunning beauty simply must be experienced to be appreciated.

Interstate 70 actually continues to descend, although not as steeply, well into the west side of the metro Denver area. It widens to six lanes in the suburb of Wheat Ridge, but for the most part stays at only six through the city of Denver. The interchange with I-25 north of downtown is called the “Mousetrap” by many Denverites due to its tangle of ramps. A short segment in Aurora, near the new Denver International Airport, does widen to eight lanes, but not for long. Not far east of the airport, I-70 is back down to four lanes heading into the edges of the metro area.

The most deathly boring part of I-70 begins here as the highway leaves the Denver area behind. It goes through nothing but flat-to-rolling plains for the rest of Colorado and halfway across Kansas, with only a handful of small towns to punctuate 400 miles (640 km) of nothingness. The elevation trends ever-so-slowly downward, from the famously “mile-high” (5,280 ft./1,609 m) Denver to around 4,000 ft. (1,219 m) at the Colorado/Kansas line, and eventually down below 1,500 ft. (457 m) by the time I-70 reaches Salina, KS, but this is not noticeable at all because it occurs over such a long distance.

After passing by Junction City and the military installation of Fort Riley, I-70 enters into a region known as the “Flint Hills.” Although the hills aren’t anywhere near as long or steep, the terrain is somewhat reminiscent of that seen further west along I-70, particularly in Utah; there are some very colorful exposed rocks here. The general elevation trend is a descent as I-70 proceeds further east, finally exiting the Flint Hills only about 15 miles (25 km) west of Topeka. There are a couple of tight, slow curves to negotiate in downtown Topeka before I-70 joins the Kansas Turnpike east of town.

Technically speaking, the Kansas Turnpike extends almost to the Missouri state line along I-70, but the tolled section ends between Lawrence and Bonner Springs. Turnpike mile and exit numbers are used instead of I-70’s numbering, meaning that numbering jumps down from 367 to 183 upon joining the Turnpike and then very suddenly jumps back up from 224 to 410 at the western city limit of Kansas City, KS. There are six lanes in the western part of “KCK,” as it is known by locals, with eight lanes beginning closer to downtown.

Just south of downtown KCK, I-70 makes a long, sweeping 90° turn to the north and goes that way for about a mile, before coming to a very tight 35-mph (56 km/h) curve back to the east to cross the Kansas River. Following the elevated Lewis and Clark Viaduct, I-70 enters Missouri very shortly thereafter and passes by the north side of downtown “KCMO” (local slang for the much larger Kansas City, MO). It follows half of KCMO’s so-called “Alphabet Loop” around downtown, heading south with U.S. Route 71 for a short distance, before heading back east and resuming its own alignment. Just east of the I-435 outer loop around both Kansas Cities, both Kauffman Stadium (Kansas City Royals) and Arrowhead Stadium (Kansas City Chiefs) are easily visible from I-70; in fact, if parking on the eastbound right shoulder were legal, that would be a good way to catch Royals games for free, from a few hundred feet beyond the outfield fence.

The terrain across much of Missouri is generally rolling, with one long descent-climb combination at the Loutre River near milepost 168. Traffic here is very heavy for a rural Interstate, and I-70 no doubt needs to be expanded to six lanes here. There are some interesting older truss bridges that carry I-70 in Missouri, including two Missouri River bridges; one of these is near Rocheport, and the other is in St. Charles.

At Wentzville, I-70 widens to six lanes, and then to eight in St. Peters, as it begins to approach St. Louis. It does so from the northwest, passing by Lambert Field (St. Louis’ main airport) and eventually through some of the city’s older neighborhoods on the way to downtown. There is a pair of reversible express lanes in the median most of the way through the city, ending just before downtown. In honor of St. Louis Cardinals slugger Mark McGwire’s 70 home runs in 1998, I-70 is named the Mark McGwire Freeway near downtown. (Kansas City, which is constantly carrying on a pissing match with St. Louis in just about anything, responded by naming its segment for 1980s Royals hero George Brett.)

In downtown St. Louis, I-70 becomes a depressed (below-grade) freeway for a couple miles; after passing the Gateway Arch, it makes a 90° turn to the east and joins the eight-lane Poplar Street Bridge (along with I-55 and I-64) to cross the Mississippi River into Illinois. This is one of only two three-way multiplexes on the Interstate system; the other one, I-39/90/94 in Wisconsin, is much longer. The multiplex with I-64 only goes on for three miles (5 km), but I-55 and I-70 stay together for the first 20 miles (32 km) in Illinois through the eastern suburbs of St. Louis.

Motorists following I-70 at this point, in Troy, IL, will notice that upon making the 90° turn back to the east to stay on I-70, the exit and mile numbers have dropped. From this point east, all exit and mile numbers along I-70 in Illinois are in fact incorrect; they are all roughly 4½ miles too low. For some reason, the exit and mile numbers along independent I-70 in Illinois are based on I-270’s distance to the Mississippi River, well north of downtown St. Louis, rather than I-70’s distance in common with I-55.

The surroundings in much of Illinois, Indiana, and western Ohio are flat cornfields without much of interest to look at. In fact, once it is sufficiently far out into St. Louis’ eastern suburbs, I-70 drops to four lanes and stays there all the way to Indianapolis. On the west side of that city, a new 10-to-12-lane express-local alignment of I-70 was built in 2004-05, south of the original six-lane one, to allow for expansion of a FedEx facility at Indianapolis International Airport. Beyond the airport, I-70 resumes its old six-lane status and heads into downtown; many downtown landmarks are clearly visible from either I-70 itself or the short I-65/70 multiplex. There is some unused grading still visible at the north I-65/I-70 split for ramps to a proposed but never built I-69 connection to downtown.

In the stretch between Dayton and Columbus, the Ohio Department of Transportation (ODOT) is doing a ton of work on I-70. The interchange with I-75, formerly a simple diamond-cloverleaf, is being converted into a stack interchange with flyover ramps; east of there, ODOT is widening most of the four-lane sections to six lanes to deal with almost-crushing traffic levels. About 20 miles (32 km) west of downtown Columbus, I-70 finally widens to six lanes for good, and stays at least that wide all the way through Columbus except for one very short stretch on the west side. The I-71 multiplex downtown is frequently congested, especially eastbound, because traffic must weave from one side to the other to stay with the same freeway (e.g., northbound I-71 traffic enters eastbound I-70 on the right, but must exit from I-70 on the left).

East of Columbus, I-70 remains fairly flat for about another 30 miles (around 50 km), then starts to head into the hill country that dominates southeastern Ohio. Some of these hills do get as steep as 4%, and there are a couple of fairly long ones, especially the one just east of downtown Zanesville and the one that runs for almost four miles down to the Ohio River. Upon reaching the Ohio, I-70 first crosses on to Wheeling Island, WV, and then utilizes a truss bridge to reach the mainland part of Wheeling. Mere yards east of the bridge, I-70 must pass through the Wheeling Tunnel, which has only one I-70 through lane in each direction (the other lane breaks off westbound and joins eastbound almost literally right at the western portal of the tunnel). Nine miles east of the tunnel, the highway climbs a two-mile, 5% grade to exit the Ohio River valley, and a mere three miles after that, you will have missed West Virginia if you blinked.

The first 20 miles in Pennsylvania are nothing to write home about, but after I-79 leaves its short multiplex with I-70 to head south, I-70 quickly becomes a terribly substandard freeway. In fact, in my opinion, it is the most substandard stretch of Interstate anywhere in America. There is no left shoulder at all; the solid yellow line sits right next to the under-height jersey barrier that separates the two directions of traffic. The right shoulder isn’t wide enough to pull off the road in many places in case of an emergency. There are absolutely no acceleration or deceleration lanes on any of the ramps, and a lot of the on-ramps even have stop signs where they meet the freeway! The Pennsylvania Department of Transportation (PennDOT) has imposed a 55-mph (88 km/h) speed limit along this 37-mile (60 km) stretch that extends all the way to New Stanton, but no improvements or plans to bypass this dangerous stretch are forthcoming.

At New Stanton, I-70 joins with the Pennsylvania Turnpike for an 86-mile multiplex to the town of Breezewood. See the Eastern Interstate 76 page for more about the Turnpike. After leaving the Turnpike, I-70 follows a short segment of freeway that was originally part of the Turnpike (until a 1960s tunnel-bypassing project) before — I kid you not — ceasing to be a freeway! Ramps carry I-70 right into U.S. Route 30, which has two traffic signals in Breezewood. Drivers desiring to stay on I-70 must go about ¼ mile west on U.S. 30, past a veritable gauntlet of motels, gas stations, truck stops, and restaurants, and then make a left turn onto an entirely different stretch of freeway. (Coming westbound into Breezewood, this freeway literally ends in a surface “T” intersection!)

The final 23 miles of I-70 in Pennsylvania run north-south, and climb over several large hills, most notably Sideling Hill at milepost 156. Again, there is a 55-mph (88 km/h) speed limit on this stretch, although this has more to do with several tight curves. Just barely over the Maryland line is the interchange with I-68, after which I-70 makes a sweeping 90° turn and heads back to the east. The first 11 miles (18 km) or so in Maryland run closely parallel to the Potomac River, before I-70 turns more to due east and leaves the Potomac behind. Up to and through Hagerstown, much of I-70 is flat to gently rolling.

Beyond Hagerstown, I-70 turns to the southeast again to head for Frederick. Near milepost 36, the highway begins a three-mile, 6% climb to 1,200-ft. (366 m) South Mountain, atop which there is a rest area where the D.C. snipers, John Muhammad and Lee Malvo, were caught in 2002. A bit further east, I-70 comes to the 980-ft. (299 m) Braddock Mountain before descending for several miles into Frederick. East of Frederick, rolling terrain dominates much of the rest of I-70 into Baltimore.

In the original plan for the Interstate system, I-70 was to run through Leakin Park and Gwynns Falls Park, parallel the Gwynns Falls creek, and eventually terminate at I-95 near the present-day Caton Avenue interchange (I-95 exit 50) on Baltimore’s southwest side. However, one of Baltimore’s many successful “freeway revolts” of the 1970s killed this project after three miles of I-70 inside I-695/Baltimore Beltway had been completed. The stub end of I-70, just barely inside the Baltimore City line, was converted into a park-and-ride lot with access to Security Boulevard, a local road that connects to some of Baltimore’s major surface thoroughfares. There is at least one westbound I-70 sign between the park-and-ride and I-695, indicating that this is in fact I-70, although this contradicts eastbound signage that states “I-70 ENDS AT I-695.” Thus it is that America’s fifth-longest Interstate comes to its ignominious end in a parking lot.